This invention relates to recording of data on an optical disc on which additional writing is possible e.g., Compact Disc Write Once (hereinafter referred to as "CD-WO") and on an optical disc from which recorded data is erasable, e.g., Compact Disc Magneto-Optical (hereinafter referred to as "CD-MO") and, more particularly, to recording of mastering auxiliary information necessary for performing a mastering processing in a large scale production of discs after making a recorded disc.
In a case where program information has been written experimentally on a writable disc such as a CD-WO or a CD-MO and thereafter a recorded disc has finally been completed through processes such as assessing and debugging, a large scale production of discs in the form of, e.g., a Compact Disc, based on the contents of the recorded disc is generally made. In a mastering process in the large scale production, various subcode information used for mastering such as TOC (table of contents) information and subcode information and user's bit to be recorded on a program area is recorded as mastering auxiliary information on a recording medium such as a floppy disc, a Bernoulli type disc (i.e., hard disc) or a magnetic tape separately from the recorded disc and this recording medium is transferred with the recorded disc to the mastering process.
In a Compact Disc or CD-WO, as shown in FIGS. 4 and 5, a train of recording pits is spirally formed with a track pitch of 1.6 .mu.m on a disc having an outer diameter of 120 mm.phi., a central opening diameter of 15 mm.phi. and thickness of 1.2 mm consisting of and three areas of a lead-in area Li, a program area Pg and a lead-out area Lo are formed from the inner periphery side by the train of recording pits to enable signals to be recorded in the respective areas. The program area Pg is an area (program area) where program information and subcode information are recorded whereas the lead-in area Li and the lead-out area Lo are areas (lead areas) where information such as TOC information which relates to a table of contents extracted from subcode information used for control of the disc is recorded.
In the lead-in area Li, TOC information representing contents of the program recorded in the disc is recorded in the subcode form. In the case of a disc containing a musical program, for example, TOC includes information such as the number of music pieces included in the disc, addresses on the disc of the beginning, end and intermediate break of each music, time for each music and total time of all music contained in the disc. The lead-in area Li is an area beginning from the innermost part of the recording area of the disc and continuing to a position immediately before the start point of the program area Pg, e.g., an area extending normally from a position of a diameter of 44.7 mm.phi. which is inside of a position of a diameter of 46 mm.phi. to the program start position. In this lead-in area Li, TOC information is repeatedly recorded. In most Compact Discs, the number of music and the total performance time of the disc are displayed upon loading of the disc in a Compact Disc player. This displayed information is obtained by reading TOC information upon loading of the disc. The TOC information is also ustilized for selecting a particular music in the disc. In the lead-in area Li, a main channel is vacant and data "0" is normally stored.
In the program area Pg, program information such as music signals and subcode information for the control purpose are recorded.
In the lead-out area Lo, a signal representing the end of the program is recorded. The lead-out area Lo is an area which, for example, extends from the end position of the program area Pg to a postion which is at least 0.5 mm outside in the radial direction (up to a maximum diameter of 117 mm.phi.). In the lead-out area Lo, lead-out information consisting of repeating pulses of 2 Hz is recorded. The program area Pg therefore is defined by the program start position of the diameter of 50 mm.phi. and the program end position (up to the maximum diameter of 116 mm.phi.). A main channel of the lead-out area also is normaly "0".
A recording format used in a case where a normal music source is recorded in a Compact Disc will now be described. The spiral recording track consisting of the train of pits is divided into blocks frame by frame and each frame consists, as shown in FIG. 6, of a synchronizing signal, a subcode, a program information bit, and alternate repetition of an error correction bit and a program information bit. The synchronizing signal of FIG. 6 is a frame synchronizing signal which is inserted at the start point of each frame. As the subcode, one byte is inserted for one frame and a predetermined subcode frame is constructed of a subcode ranging over plural frames. The subcode is also called control information which includes various information for control of the disc and information enabling the user to use the disc easily. As the subcode, eight channels of P, Q, R, S, T, U, V and W channels are defined. In the narrow sense of the term, the P and Q channels are sometimes called a subcode and the R-W channels are called user's bits. The program information bit is program information itself consisting of information such as digital audio information of a music to be recorded. The error correction bit is data for correcting an error to the program information. The code portion other than the synchronizing signal and the subcode in each frame constitutes a main channel which is a recording channel for main information such as a program to be recorded. In this example, the code portion of the program information bit, error correction bit, program information bit and error correction bit constituting the main channel will be called a main code. In the case of normal recording of digital audio information of a Compact Disc, as shown in FIG. 7, audio signal data of a left channel L and a right channel R each having 2 bytes are alternately recorded in the program information bits of the main channel.
In manufacturing a Compact Disc, it is a normal practice to produce a digital master tape which was recorded program information to be recorded into a Compact Disc, insert subcodes such as P and Q in the program information of the digital master tape, apply TOC information as table-of-contents information obtained from these subcodes to be recorded in the lead-in area Li and apply information to be recorded in the lead-out area Lo, thus producing a Compact Disc tape master including all information to be recorded in a Compact Disc. A glass master is then produced by applying laser cutting to a glass master original disc on the basis of the Compact Disc tape master and then a metal master, a metal mother and a stamper are sequentially made on the basis of the glass master. Transparent discs are produced in a large scale by pressing using this stamper (e.g., by injection compression forming). Compact Discs are completed by forming a reflecting film and protective film on each disc.
When a complete disc has been produced by assessing and debugging a disc produced as a CD-WO by using a disc recording system for a CD-WO and by reproducing, when necessary, a corrected disc, Compact Discs are produced in a large scale by using the completed disc as a master disc. In this case, when mastering, i.e., production of a Compact Disc master, is performed by using only a CD-WO, there is likelihood that information such as TOC and subcode, user's bit recorded in the subcode form becomes data containing much error due to poor forming of the CD-WO pits. For this reason, it was necessary in the past in mastering of a Compact Disc to record mastering auxiliary information necessary for mastering including TOC, subcode and user's bit etc. in a floppy disc, magnetic tape or other recording medium separately from the CD-WO. In other words, in mastering of a Compact Disc from a CD-WO, a recording medium such as a floppy disc or a magnetic tape on which mastering auxiliary information such as TOC, subcode and user's information is recorded must be transferred with the recorded CD-WO to the mastering process. In the mastering process, a master is made according to a predetermined format on the basis of these information. This preparation of extra recording medium containing mastering auxiliary information is a troublesome process.
It is, therefore, an object of the invention to provide an optical disc, and a method and a device for recording data on an optical disc which simplify the work and protocol for performing a mastering of a Compact Disc or the like from a writable optical disc and yet enables an accurate mastering.